1. Field of the Invention
The present invention relates to a device used in sequential forming. The sequential forming is a well-known method whereby a pushing member of a bar shape, a convex shape or a concave shape is provided to push on a metal member such as a metal sheet, wherein the metal member and the pushing member are caused to move relatively to have the plate member formed into a predetermined three dimensional shape such as a shell shape. In the present invention, two axial directions perpendicular to each other within a plane of the plate member before forming are referred to X and Y, while an axial direction perpendicular to each of them is referred to Z.
2. Description of the Prior Art
The sequential forming and the sequential forming device are disclosed in WO99/38627 and the like. For example, the sequential forming is disclosed in Japanese Unexamined Patent Publication No. Hei 5-42328 (1993). According to this sequential forming, four corners of a plate member are horizontally supported by crease controllers, and a lower pushing member of a convex shape is pushed up onto the plate member from below to have the plate member preliminarily drawn into a rough shape. By pushing a bar-shaped upper pushing member onto the plate member from above to move the plate member in the directions of X and Y and then moving the pushing member in the Z direction, a desired three-dimensional shape is formed.
In a conventional sequential forming, a plate member is extended or rolled by a bar-shaped pushing member to copy the surface of a lower pushing member formed as a convex die for forming. In this case, a shape of the formed surface is generally not uniform and thus the plate redundancy is caused. Accordingly, in an outer sheet for an automobile or the like which has a gently curved surface and the shape is not provided with high rigidity, creases are caused on the periphery. Since the pushing member with high rigidity is pushed onto the plate member in a point contact condition, there is easily caused striped tool marks on the surface of the plate member. It is therefore an object of the present invention to provide a sequential forming device which can prevent such creases or tool marks from being produced.
To solve the problems above, a sequential forming device according to one aspect of the present invention comprises a plate member having the periphery supported and a bar-shaped pushing member adapted to push on the plate member from one side, wherein a contacting section between the plate member and the bar-shaped pushing member is caused to move in the three-dimensional direction to have the plate member formed into a predetermined three-dimensional shape, characterized in that a section of the bar-shaped pushing member contacting with the plate member is a flexible member.
The sequential forming device according to another aspect of the present invention comprises a plate member having the periphery supported, a bar-shaped pushing member adapted to push on the plate member from one side, a die-shaped pushing member adapted to push on the plate member from the other side, the plate member being inserted between the bar-shaped pushing member and the die-shaped pushing member, wherein a contacting section between the plate member and the bar-shaped pushing member is caused to move in the three-dimensional direction to have the plate member formed into a predetermined three-dimensional shape, characterized in that the die-shaped pushing member is concave die.
The sequential forming device according to yet another aspect of the present invention includes a flexible member which is hemispheric.
The sequential forming device according to yet another aspect of the present invention includes a flexible member which is cylindrical and pivotably supported onto a tip section of the bar-shaped pushing member.
According to the present invention, since a section of a bar-shaped pushing member contacting with a plate member is a flexible member, the section does not make a point contact with the surface of the plate member when formed. It is therefore possible to prevent the tool marks from being produced.
Since the die-shaped pushing member is a concave die, the plate member is pushed and spread into the concave space of a lower die by the bar-shaped pushing member for forming. In this manner, it is possible to prevent the creases from being produced on the periphery of the forming section. Further, since the contacting section of the bar-shaped pushing member with the plate member is a flexible member, it is also possible to prevent the tool marks from being produced.
Since the flexible member is hemispheric, it makes a spherical contact with the plate member. Accordingly, the contacting section between the bar-shaped pushing member and the plate member becomes large to make the movement smooth. It is also possible to prevent the tool marks from being produced.
Since the flexible member is cylindrical and pivotably supported onto the tip section of the pushing member, the flexible member is adapted to contact the surface of the plate member rolling thereon. Accordingly, less friction results between the pushing member and the plate member thereby making the movement smooth.